public class Solution14 {
    public String longestCommonPrefix(String[] strs) {
        if(strs==null||strs.length==0){
            return "";
        }
        String prefix=strs[0];
        int count=strs.length;
        for(int i=1;i<count;i++){
            prefix=longestCommonPrefix(prefix,strs[i]);
            if(prefix.length()==0)
            {
                break;
            }
        }
        return prefix;
    }

    public String longestCommonPrefix(String str1, String str2) {
        int length = Math.min(str1.length(), str2.length());
        int index = 0;
        while (index < length && str1.charAt(index) == str2.charAt(index)) {
            index++;
        }
        return str1.substring(0, index);
    }
}
